This invention relates to surgical stapler apparatus, and more particularly to surgical stapler apparatus having a longitudinally curved shaft intermediate the portion of the apparatus which performs the stapling function and the actuator portion of the apparatus.
There are several known types of surgical staplers in which the stapling function takes place at a location which is reletively remote from the location at which the stapler is held and actuated by the operator. One example of such stapers are the linear closure surgical staplers shown illustratively in Green et al. U.S. Pat. No. 3,494,533. Another example of such staplers are the circular anastomosis surgical staplers shown illustratively in Conta et al. U.S Patent No. 4,304,236. Typically, in instruments of the types exemplified by these references, tissue to be stapled is clamped between an anvil assembly and a staple holding assembly, both of which are located at the distal end of the instrument. The clamped tissue is stapled by driving one or more staples from the staple holding assembly so that the ends of the staples pass through the tissue and are clinched by contact with the anvil assembly. The forces required to operate the instrument are applied by the operator of the instrument to one or more actuator elements located at or near the proximal end of the instrument. The distal and proximal portions of the instrument are joined by a longitudinal connecting shaft structure along which the actuating forces and motions are transmitted to lhe distal operating elements. This type of construction, including relatively widely spaced distal and proximal portions, may be employed for any of several reasons such as the relative inaccessibility of the tissue to be stapled, the need for good visibility of the tissue during stapling, and the like.
In some applications of instruments of the tYpes mentioned above it may be desirable for the longitudinal shaft structure joining the distal and proximal portions of the apparatus to have a longitudinal curve. This may facilitate placement of the instrument in particular body structures, it may facilitate reaching remote or relatively inaccessible stapling sites, or it may allow the staples to be presented at the stapling site at a predetermined angle relative to the operator of the instrument. However, this type of instrument construction means that the actuating forces and motions must be transmitted along a curved structure, which is a considerable complication in the design of the instrument. In addition to requiring that the structure be capable of transmitting actuating forces and motions around a curve, the structure must generally transmit these forces and motions without significant change in curvature ("deflection") of the instrument, and without significantly greater losses due to friction than would be present in a comparable straight instrument. Both the control of deflection and the control of friction losses are much more diffioult in a curved instrument than in a comparable straight instrument.
Another complicating factor in designing curved surgical stapling instruments is the increasing interest in surgical instruments which can be economically discarded after use in a single surgical procedure, i.e., so-called disposable instruments. Typically, a disposable instrument is sold in sterile condition in packaging designed to keep the instrument sterile until used. After the instrument has been used in a surgical procedure, it is discarded. In this way all difficulty and expense associated with cleaning, sterilizing, and reloading the instrument are entirely avoided.
For an instrument to be economically disposable after use in only one surgical procedure, however, the cost of the instrument must be relatively low. This generally dictates that as much as possible of the instrument be made of inexpensive materials such as plastics, and that the instrument have the simplest and lightest possible construction. None of these criteria for an economically disposable instrument is readily compatible with the requirements for a curved instrument. For example, the problem of deflection of the curved structure could be reduced or eliminated by using a relatively heavy construction or more expensive stronger materials, but both of these solutions are directly contrary to the needs of a disposable instrument.
In view of the foregoing, it is an object of this invention to provide improved surgical staplers of the type having a curved shaft structure between the distal stapling elements and the proximal actuating elements.
It is another object of this invention to provide economically disposable surgical staplers of the type having a curved shaft structure between the distal stapling elements and the proximal actuating elements.